1. Trondheim Tekniske Fagskole Michel Olagnon IFREMER Brest, France Sar-Drift: Drifting at sea, whence and whereto ?

2. Trondheim Tekniske Fagskole With material from: Sar-Drift: Drifting at sea, whence and whereto ? Øyvind Breivik Art Allen José Perez Marrero Marc Pavec Marc Le Boulluec Christophe Maisondieu Emmanuel Mansuy Bertrand Forest

3. Trondheim Tekniske Fagskole Outline Problem and context. Uncertainties involved: - metocean - aerodynamics - hydrodynamics A few State-of-the-Art systems. Sar-Drift results: - Basin tests - Examples (Napoli) - Perspectives (field tests)

4. Trondheim Tekniske Fagskole Problem Every day, objects are drifting at sea when we would want to have them back onshore or at least to know precisely where they are.

5. Trondheim Tekniske Fagskole Problem Statistics of the use of MOTHY, French drift prediction system.

6. Trondheim Tekniske Fagskole Problem Containers.

7. Trondheim Tekniske Fagskole Problem Small crafts.

8. Trondheim Tekniske Fagskole Problem Illegal immigrants.

9. Trondheim Tekniske Fagskole Problem Person In Water (PIW)

10. Trondheim Tekniske Fagskole Problem Self-locating marker buoys may not always drift as the object of interest, or may have failed to be deployed.

11. Trondheim Tekniske Fagskole Objective To generate search areas for the Search and Rescue Services based on the best available wind and current information To paraphrase Einstein: Make search areas as small as possible, but not smaller Challenge

12. Trondheim Tekniske Fagskole Search Maths POS = POD x POC POS: Probability of success (do we find what we are looking for?) POD: Probability of detection (the keen eyes of the rescuers) POC: Probability of containment (are we searching in the right place?), our business.

13. Trondheim Tekniske Fagskole The Uncertainties Involved Where and when did the accident take place? Which object should we look for (life raft, person in water, …)? What are the wind and wave conditions like in the area? What are the surface currents in the area? How does the object move when submitted to wind, waves and current?

14. Trondheim Tekniske Fagskole Metocean Uncertainties Wind and wave conditions Meteorological forecast models are good… in average, but often wrong on the precise timing of changes in speed and direction. Current Quick-varying and strong in tidal-dominated areas. Wind-dependence in addition to ”normal”.

15. Trondheim Tekniske Fagskole Metocean Uncertainties The directions to go: Improve the quality of forecast (nowcast) of sea state conditions, and provide associated ”confidence intervals”. Solve the logistics problem of making that information readily available to those who need it. Be able to post-enhance forecast information from actual field observations.

16. Trondheim Tekniske Fagskole Aero- & Hydro-dynamics Wind speed and object drift is approximately linearly related Different objects drift differently Life raft with drogue Undrogued life raft

17. Trondheim Tekniske Fagskole Aero- & Hydro-dynamics Waves induce slow- drift on objects, and swell often coexists with the [locally generated] wind sea, so the use of a single mixed coefficient for wind and waves may not always be appropriate.

18. Trondheim Tekniske Fagskole Empirical leeway data 63 classes of SAR objects have been compiled by the U.S. Coast Guard through extensive field campaigns and were generously made available to the project.

19. Trondheim Tekniske Fagskole Leeway divergence Objects do not drift exactly downwind!

20. Trondheim Tekniske Fagskole Leeway divergence Objects drift at an angle to the wind (the leeway divergence angle) Symmetry allows stable drift left and right of downwind. This leads to a diverging search area as time progresses

21. Trondheim Tekniske Fagskole Drift models Several nations have developed drift models that enable to define search areas NORWAY: LEEWAY

22. Trondheim Tekniske Fagskole Drift models USA: SAROPS

23. Trondheim Tekniske Fagskole Drift models SWEDEN: BADIS

24. Trondheim Tekniske Fagskole Drift models UK: SARIS

25. Trondheim Tekniske Fagskole Drift models FRANCE: MOTHY

26. Trondheim Tekniske Fagskole Drift models POLAND

27. Trondheim Tekniske Fagskole Drift models All those models have in common a simple way to take into account uncertainties: run many cases perturbating the conditions in a rather empirical manner. Most of them rely on international collaboration for their inputs, as well for metocean forecasts as for drag coefficients. In the Sar-Drift project, we want to improve the stochastic descriptions of metocean forecasts and drag coefficients and to have a system with the ability to accept and make full use of those improved descriptions.

28. Trondheim Tekniske Fagskole In the present version of most drift codes, waves are not present (or they are represented by an artifical increase in the wind drag coefficients).  Need to get information from Ifremer basin tests… Drag coefficients

29. Trondheim Tekniske Fagskole Tank-Containers and Barrels Standard dimensions 20’ x 8’ x 8’6 ’’ (6.1m x 2.44m x 2.59m) – Max. Gross 30.5 t – Tare4.2 t – Max Payload26.3 t Oil drums – Diameter 0.6 m – Height1.21 m – Volume 200 l (55 gal) Coefficients for other objects

30. Trondheim Tekniske Fagskole IFREMER wave tank in Brest Length: 50 m Width: 12,5 m Depth: 10 m and 20 m Wave maker : Regular and irregular waves Max. wave height (crest-to-trough): 50 cm. Range of Periods [0.8s – 3.5 s].

31. Trondheim Tekniske Fagskole Tests carried out in September 2006 with 1/8 th models of 20 ft and 40 ft containers. Basin tests at Ifremer

32. Trondheim Tekniske Fagskole Tests carried out in July/August 2007 with wind and with other models. Basin tests at Ifremer

33. Trondheim Tekniske Fagskole First results on drift speed due to waves show computations are not too bad. Basin tests at Ifremer

34. Trondheim Tekniske Fagskole Qualitative observations: In some conditions, fast drift, up to more than 2 knots real scale. Basin tests at Ifremer

35. Trondheim Tekniske Fagskole Qualitative observations: Though head- and beam-orientations favoured, transverse lift does occur with waves only. Basin tests at Ifremer

36. Trondheim Tekniske Fagskole First impressions: Waves and wind should be considered separately when possible for objects of the size of a container. Tests are very instructive. Basin tests at Ifremer

37. Trondheim Tekniske Fagskole Basin tests at Ifremer Videos of the tests

38. Trondheim Tekniske Fagskole Preliminary conclusions: Need to improve the modeling of drag and drag uncertainties in the drift simulation software packages. Numerical hydrodynamic modeling can help develop the variety of the databases in addition to basin tests. Basin tests at Ifremer

39. Trondheim Tekniske Fagskole Program Animated drifts

40. Trondheim Tekniske Fagskole MSC NAPOLI

41. Trondheim Tekniske Fagskole MSC NAPOLI

42. Trondheim Tekniske Fagskole MSC NAPOLI Cookies Cookies and oil pellets arrived and started stranding on the North coast of Brittany on 25th of January. Could they come from the beached wreck ?

43. Trondheim Tekniske Fagskole MSC NAPOLI Cookies Most likely they came rather from losses during the towing operations !

44. Trondheim Tekniske Fagskole Perspectives Field tests with Norwegian Coast Guards in the Ekofisk area

45. Trondheim Tekniske Fagskole Perspectives Improve the modelling of drift Improve the inputs to drift programs Provide tools to optimize search operations

46. Trondheim Tekniske Fagskole Perspectives We need to build on our strong points: International collaboration, with informal and formal exchanges. To this aim, we will set up a 3rd International SAR workshop in SeaTechWeek 2008 in Brest. Scientific quality. We want to raise interest in the scientific laboratories working in hydrodynamics and stochastics for the topic of search of drifting objects by publishing papers and offering PhD. scholarships. Media interest. We depend almost exclusively on public funding, and “buzz-topics” get much more chances to be funded.